setup_domain_email

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the behavioral burden. It discloses the Proof account requirement and the session-flow requirement ('sign in with start_login — a session opens this tool — then call this tool again'). It does not mention side effects, reversibility, or what configuration changes are made.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The main purpose is front-loaded in two sentences, and the ACCESS instructions are separated into their own paragraph. There is slight redundancy between 'Set up email sending' and 'Configures the domain for sending verification emails', but the overall structure is compact and readable.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The definition covers the authentication prerequisite and basic input semantics, which is enough to attempt a call with id and from_email. However, it lacks return behavior, success signaling, and explicit relationship to related domain email verification tools, and there is no output schema to fill those gaps.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents 'id' and 'from_email'. The description's 'custom address' phrase adds no technical detail beyond the schema, so it stays at the baseline.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

Description states a specific action: 'Set up email sending for a verified domain' and clarifies it configures sending verification emails from a custom address. This distinguishes it from verification-oriented tools like verify_domain and start_domain_email_verification, though it does not explicitly name those alternatives.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies it should be used for an already-verified domain and to set a custom from-address, and it provides auth prerequisites. However, it gives no explicit when-to-use vs. alternatives guidance and does not mention which sibling tools should be used instead in other scenarios.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.